Electric contact



Feb. 25,1941. W.C.FURNAS 2,233,124

ELECTRIC CONTACT Filed Feb. 5, 1940 lZ/ .2Q

v I W 66% ZZMW Mw ATTORNEY.

Patented Feb. 25, 1941 UNlTED STATES PATENT OFFICE- ELEGTRICCONTACT William C. Furnas, West Allis, Wis. ApplicationFebruary 5, 1940, Serial No. 317,247

8 Claims.

The present invention relates generally to improvements in the art of transmitting electric current, and relates more specifically to improvements in the construction and operation of electrlc switch contacts and the like.

Generally defined, an object of the invention is to provide an improved switch cont-aotwhlch is simple, compact and durable in construction, and which is moreover highly efiicient in use.

A more specific object of my present invention is to provides. new and useful electric switch contact assemblage which can be quickly and firmly attached to a support, and which will not loosen due to repeated operation of the switch.

Another specific object of this invention is to provide an improved switch contact adapted to be rigidly attached to a relatively brittle support without chipping, cracking or otherwise damaging the latter.

A further specific object of my invention is to provide a switch contact structure with which aterminal may be quickly associated so as to provide an effective electric connection, and from which the terminal may be just-as readily de- 7 tached.

An additional specific object of my present invention is to provide, a simplified and more dur-' able stationary con-tact for electric switches or the like, having a contact face formed of material of relatively high electrical conductivity, such as silver. 7

Still another specific object 01' the invention is to provide an improved switch contact structure 35 comprising several parts which may be conveniently assembled to provide a compact and ex tremely durable construction in which the parts are properly insulated.

Another specific object of my invention is to 40 provide a simplified stationary contact for electrical devices which is firmly fixed against possible rotation or other displacement, and which can be manufactured and assembled at moderate cost.

A further specific object of the present invention is to provide an improved electrical contact especially adapted for use in switch assemblages of the fluid pressure actuated type and as shown in the co-pending Furnas and Hansen application, Serial No. 233,520, flied October 6, 1938.

so These and other specific objects and advantages of my present invention will be apparent from the following detailed description.

, A clear conception of an embodiment of the several features constituting my present inven tion, and of the mode of constructing, of assemmovable contact; and

Fig. 2 is an exploded perspective view showing thetseveral parts of the improved electrical contac While the invention has been shown and dem scribed herein as having been specifically embodied in a silver faced contact applied to a fixed suppont, it is not my desire or intent to thereby unnecessarily restrict the scope or utility of the improvement.

Referring to the drawing, the improved contact portion or the switch assembly shown in Fig. 1, comprises in general a fixed contact support or plate t formed. of relatively brittle moulded insulating material and having a polygonal hole or 25 through opening 5 therein; a reeniorcing plate or bar ii formed of similar insulating material, and having therein a circular hole i in substantial alinement with the opening ii; a stationary contact 8 formed of relatively ductile metal suchas copper or brass and having a harder contact facing 9 formed of silver or the like, at its extreme lower end, a threaded bore it above the facing 9, and a smooth bore i i at its upper end, the contact 8 also being provided with a polygonal section i2 adapted to fit the support opening 5 and with an approximately cylindrical outer portion it which is snugly cooperable with the bar hole 1; a cup shaped washer it having a polygonal hole I5 therein adapted to receive the upper end portion of the contact 3, and to be riveted in place by distortion of the extreme upper end it; a removable biiurcated terminal ll adapted to fit within the rimv it of the washer i4 and to coact with the flanged contact end i6; a terminal clamping screw it) having a threaded shank 20 engageable with the threaded bore ill of the contact 8, and being provided with a slot-ted head 2| which is ccoperable with the terminal II; a movable con tact 22 having a contact facing 23 adapted to en-' gage the facing 9 of the contact 8, and being provided with an actuating stem or support 24; and a compression spring 25 coacting with the movable contact 22.

The supporting plate 4 and reenforcing bar 6 may be of the general shape and may be mounted as shown in co-pending application Serial No. 233,520, and the movable contact 24 may be actuated in any suitable manner as my mechanism such as shown and described in said application. The plate 4 and bar 6 are preferably formed of insulating material, and while these parts may be formed integral with each other, the cost of manufacture may be minimized by utilizing standard sheet stock and by rigidly interconnecting the two pieces with the aid of the fixed contact 8 and washer I4.

The improved stationary contacts 8 which are formed 'of rather ductile metal having good electrical conductivity, are preferably constructed by first forming the central alined bores III, II therein and by threading the bore I0, after which the silver contact facing 9 may be brazed, soldered or otherwise firmly attached to the lower heade'd end of each contact 8 to close the bore I therein. Aftereach contact 8 has been thus properly initially formed, it will appear as shown at the bottom of Fig. 2, and it may thereafter be applied to the alined opening and hole I in a plate 4 and bar 8 from beneath. While the opening 5 and contact section l2 are shown as being square, these parts may be of any other polygonal shape which will prevent the contact 8 from rotating after insertion thereof within the plate 4. The upper section I3 of each contact 8 is preferably circular in external cross-section, but may be slightly tapered so as to facilitate assembly; and the washer opening I5 should rather snugly engage the upper end of the'contact 8 when these parts are assembled preparatory to rivetting, so as to centralize the washer I4 relative to the contact 8. When the plate 4, bar 6, contact 8, and washer I4 has been assembled and the extreme contact end I6 has been peened over or rivetted as in Fig. 1, the plate 4 and bar 8 will be rigidly united and the contact 8 cannot rotate or move in any direction relative to its support. While the washer opening I5 is shown as being hexagonal, it may be of any other polygonal shape; and such polygonal shape is preferable in order to prevent rotation of the washer I4 relative to the contact 8 afterrivetting has been effected.

The terminal I! is of standard and well known construction, and is shown bifurcated in order to permit the same to be applied laterally to the attaching screw I9 and within the retainingsocket formed by the rim I8 of the washer I4.. This rim I8 may be locally interrupted as shown in Fig. 2 in order to clear the terminal I1; and when the cap screw I9 is driven home .within the threaded bore III of the contact 8,

the terminal I! will be held in intimate contact with the end I6 of the contact 8 and will be in direct electrical communication with the facing 8 which is integrally connected to the contact 8. The enlarged bore II in the upper end of the contact 8, obviously facilitates rivetting' of the contact end l6 by thinning the metal at the zone of rivetting, and also avoids marring the threads in the bore I0 during the fastening operation.

From the foregoing detailed description it will be apparent that my present invention -provides an extremely simple, compact and durable contact assemblage which can be quickly and firmly attached to a relatively brittle support, without danger of damaging the support. By

virtue of the fact that the facing 8 is formed integral with the contact 8, and that the terminal I1 is caused to coact directly with the opposite integral end of this contact, most effective electrical connection is assured when the screw I9 is driven home. The polygonal formation of the opening 5, contact portion I2, and of the opening I 5 in the washer I4, will obviously prevent possible rotation of the several parts rela ive to each other, when the screw [9 is applied to a terminal I1, and the flanged end I6 will effectively prevent separation of the parts due to repeated operation of the switch. The improved contact assemblage has proven highly satisfactory and successful in actual commercial use, and the contacts can be quickly applied and will permit the use of several superimposed supporting plates, thereby minimizing the cost of construction of the switch assemblage.

-It should be understood that it is not desired to limit the invention to the exact details of construction, or to the precise mode of use, herein shown and described, for various modifications within the scope of the claims may occur to persons skilled in the art.

' I claim:

1. A. contact assemblage comprising, coacting supporting plates having polygonal and circular alined openings, a washer coacting with one of said plates adjacent said circular opening, an internally threaded contact having polygonal and circular portions snugly coacting with said polygonal and circular openings, respectively, said contact also having end portions formed to clampsaid plates and said' washer together, and a terminal attaching screw coacting with the internal threads of said contact.

2. A contact assemblage comprising, a support having an opening therein, a washer coacting with said support adjacent said opening and having a polygonal hole therethrough, a hollow contact fitting said opening and said hole and being rivetted to said washer, said contact having a threaded bore and an enlarged smooth bore located adjacent the rivetted outer end thereof, and a terminal attaching screw coacting with said threaded bore and being of lesser diameter than said smooth bore.

3. A contact assemblage comprising, a pair of supporting plates having polygonal and circular alined openings, a washer coacting with one of said plates adjacent said circular opening and having a polygonal hole alined with said opening, a contact having polygonal and circular portions coacting with said openings and with said hole and having a headed end portion coacting with one of said plates, said contact having a threaded bore and an enlarged smooth bore remote from the headed end thereof and the portion of said contact adjacent said smooth bore being rivetted over said washer, and a terminal attaching screw adjustably associated with said threaded bore and having a head cooperable with the rivetted portion of said contact. a

4. As an article 'of manufacture, a switch contact having a headed end and polygonal and circular sections, the interior of said contact being provided with a. threaded bore adjacent said headed end and with a larger bore adjoining said circular portion and extending to the end of said contact remote from the head.

5. An article of manufacture comprising, a switch contact having its major portion formed of ductile metal and having a. facing of harder metal, fl'ihe in'tefior or :said mofitac't radiace'nt :saiid harder "metal! =beinwg iprovided with ':a :threaded.

:bone :and stihe' end 10! said ccontact remote from said harder :me'taJ being :0! sneduced thickness to 6. an m-ltiele of manufacture, a switch contact compzising a tubular iporfilon formed 10'! d-uctile metal and a contact kfacing rfor-medof .iharder metal, "the exterior of saIid zcontact being :provided vw ith polygonal and circular rsurfaces =and the interior thereof fha-v'ing &a. threaded bone adjacent said polygonal surface and having an enlarged smooth 'rbore :adiacerit the end of said circular surface.

7. As an antidle of manufacture, a .switqh con tact "having a headed end and polygonal and circular sections, ltheeinteflor of said contactbeing provided with a. threaded bore adjacent said headed end and an unthreaded bore adjoining said circular por tiomandextending to the end of said contact remote from the head.

'lygonal and circular portions flfifiug we r I and said holes respeetively, 'saiid mozita'dt imw ing 1'8. contact memblue We; :a 51mportin: plate #hevln: so opening, a second plate one mwmeh awaits supporting plate and 2a, Thole aligned with said opemnz, 2. met the opposite "side of sei'dseeond a polygonal :hole :sa i'd a contact having a head engages-file *wiflh supporting 'jplate .ami mmvi'ded "with rz'mm,

an internal thread and being of iflitokmass at the end thereof remdte imam rsaiid and adjoining said washer to ifae'fli'baite flvetifiiug of said reduced end within said zpolygonafi wareher hole, and a. terminal abtaclfing rsorew rcoadt ing with said serew 

